If two triangles are similar, then their internal angles have the same measure.
Since the internal angles of any triangle must sum to 180º, then the angle R must have a measure of 50º and the angle A must have a measure of 50º.
Nevertheless, notice that angles C and B have a measure of 65º while the angles S and T have measures of 67º and 63º respectively.
Since not all the angles from triangle ABC match those of STR, then, these triangles are not similar.
